1. Field of the Invention
The present invention relates to a cable retractor assembly and method for taking up slack of a flexible cable which is carrying power and/or data signals across a variable distance between a stationary base member and a mobile member and, more particularly, to a cable retractor assembly and a method which incorporates a spool assembly to maintain the flexible cable in a taut condition and two portions of cable to maintain continuous cable connection between the two members.
2. Description of the Prior Art
There is a need for managing variable length of excess flexible cable connected between two members wherein the distance between the members is variable. It is desirable to maintain the excess length of cable in a taut condition between the members. Otherwise, the slack cable may twist, flap or entangle with itself or with a nearby structure when the cable is caused to move with the mobile member.
The typical means for taking up the slack of a cable between a mobile member and a stationary base member is to utilize a cable of a elastic coiled configuration similar to that of a coil spring. A familiar example of a device in which such a coiled configuration is applied is the common telephone system, wherein a coil of cable is utilized between the handset and the main body of the telephone set. As the handset is moved away from the main body of the telephone, the cable coil is stretched accordingly. The cable coil retracts like a coil spring when the handset is returned to the hook on the telephone.
FIG. 1 shows a similar cable coil of the prior art configuration provided in a manipulator system to transmit power from the stationary power source to a mobile manipulator assembly. The manipulator system is described in detail in a copending U.S. patent application Ser. No. 06/720,577 filed on Apr. 8, 1985, now abandoned and refiled as continuing application Ser. No. 06/935,121. The manipulator assembly 10 driven by power from a remote power source 16 is movable vertically along a shaft 18 to thereby vary the distance between the manipulator assembly and the stationary power source. The cable coil 14 is elastic such as to allow for the movement of the manipulator assembly. As the cable coil contracts, it takes up slack in the cable connection between the manipulator assembly and the stationary source. If a straight length of cable is used instead of a coiled cable, then as the manipulator assembly moves downwards, the cable slackens and any subsequent motion of the manipulator assembly would create the possibility of entanglement of the cable with the nearby structure or entanglement with itself into a knot. Also, as the manipulator assembly moves along the shaft at high speed, the slack cable tends to flap under its inertia.
Although a coiled cable configuration is less prone to tangling than a flat cable, its use does not completely eliminate the problem. Furthermore, its benefits are somewhat offset by the fact that it may necessitate custom fabrication, i.e., a conventional ribbon-type multiconductor cable cannot be used.